Fail free remotely operated vehicle

ABSTRACT

A remotely operated vehicle comprising a flying lead orientation tool (1) and a mating tool (2), wherein the mating tool is connected to the remotely operated vehicle via the flying lead orientation tool, wherein said flying lead orientation tool comprises a first part of a locking mechanism (3), said mating tool comprises a second part of the locking mechanism (4), said first part engaging with the second part to secure the mating tool to the flying lead orientation tool in use, and wherein the locking mechanism comprises a retaining means, said retaining means permitting the disengagement of the first and second parts when the retaining means is in a first position, said retaining means preventing the disengagement of the first and second parts when the retaining means is in a second position, wherein the retaining means is biased into the first position by a biasing means.

This invention relates to a remotely operated vehicle. The invention also relates to a method of connecting a flying lead orientation tool of a remotely operated vehicle to a mating tool.

BACKGROUND

Remotely operated vehicles (ROVs) are commonly employed in subsea environments to carry out operations at underwater hydrocarbon extraction facilities. One such operation is the connection of flying leads to underwater structures via a stabplate.

Stabplates are a type of multiple quick connect (MQC) plate wherein a fixed stabplate bearing electrical or hydraulic connectors is attached to an underwater structure and a mobile stabplate bearing connectors attached to flying leads or jumper cables (for example, copper electrical lines, fibre optics, hydraulic fluid lines, etc.) is moveable by an ROV. The mobile stabplate may be mated to the fixed stabplate by an operation of the ROV, for example the extension or retraction of a tri-probe of the ROV.

During the mating and de-mating operations, the ROV becomes temporarily attached to the underwater structure via the stabplates. If power to the ROV is lost during the mating or de-mating operation it is possible that the ROV become stuck to the underwater structure. The removal and retrieval of stuck ROVs is extremely time consuming and expensive, as it necessitates either the deployment of a diver to the underwater structure, or the deployment of a second ROV.

It is an aim of the present invention to provide a ‘fail free’ ROV, i.e. an ROV that becomes disengaged from a stabplate or underwater structure if it loses power during a mating or de-mating operation.

This design requirement is the subject of ISO specification number 13628-8, under which the ROV must ‘fail free’ under power failure. The present invention aims to meet this requirement by providing a flying lead orientation tool (FLOT) that can break away mechanically from the ROV to enable the ROV to be retrieved under a loss of power, or other failure preventing operation of the ROV.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the present invention there is provided a remotely operated vehicle comprising a flying lead orientation tool and a mating tool, wherein the mating tool is connected to the remotely operated vehicle via the flying lead orientation tool, wherein said flying lead orientation tool comprises a first part of a locking mechanism, said mating tool comprises a second part of the locking mechanism, said first part engaging with the second part to secure the mating tool to the flying lead orientation tool in use, and wherein the locking mechanism comprises a retaining means, said retaining means permitting the disengagement of the first and second parts when the retaining means is in a first position, said retaining means preventing the disengagement of the first and second parts when the retaining means is in a second position, wherein the retaining means is biased into the first position by a biasing means.

The remotely operated vehicle could further comprise an actuator operable to move the retaining means from the first position to the second position, wherein the actuator requires a constant energy input to maintain the retaining means in the second position. The energy input could be provided by electrical or hydraulic means. The retaining means could comprise a latch.

The first part could contact the second part at two separate points when they are engaged with one another.

The second part could comprise a guide for the first part. The guide could comprise a slot that progressively narrows.

The second part could comprise an urging means configured to urge the first part away from the second part. The urging means could comprise a spring ejector.

In accordance with a second aspect of the present invention there is provided a method of connecting a flying lead orientation tool of a remotely operated vehicle to a mating tool comprising:

providing said flying lead orientation tool with a first part of a locking mechanism;

providing said mating tool with a second part of the locking mechanism;

engaging the first part with the second part to secure the mating tool to the flying lead orientation tool;

providing the locking mechanism with a retaining means, said retaining means permitting the disengagement of the first and second parts when the retaining means is in a first position and preventing the disengagement of the first and second parts when the retaining means is in a second position; and

biasing the retaining means into the first position with a biasing means.

The method could further comprise the step of:

providing the remotely operated vehicle with an actuator operable to move the retaining means from the first position to the second position, wherein the actuator requires a constant energy input to maintain the retaining means in the second position. The energy input could be provided by electrical or hydraulic means.

The retaining means could comprise a latch.

The first part could contact the second part at two separate points when they are engaged with one another.

The second part could comprise a guide for the first part. The guide could comprise a slot that progressively narrows.

The second part could comprise an urging means configured to urge the first part away from the second part. The urging means could comprise a spring ejector.

DETAILED DESCRIPTION

The invention will now be described by way of example with reference to the accompanying drawings, in which:

FIG. 1 shows a perspective view of a flying lead orientation tool and a mating tool in accordance with the present invention;

FIG. 2 shows a perspective view of the flying lead orientation tool and mating tool of FIG. 1 from a different angle;

FIG. 3 shows a side view of the flying lead orientation tool and mating tool of FIG. 1 prior to engagement of the first and second parts of the locking mechanism;

FIG. 4 shows the same side view as FIG. 3 after engagement of the first and second parts;

FIG. 5 shows an underside view of the flying lead orientation tool and mating tool of FIG. 1 prior to engagement of the first and second parts;

FIG. 6 shows the same underside view as FIG. 5 after engagement of the first and second parts;

FIG. 7 shows a perspective underside view of the flying lead orientation tool and mating tool of FIG. 1 after engagement of the first and second parts;

FIG. 8 shows a perspective view of a flying lead orientation tool suitable for use with the present invention;

FIG. 9 shows the flying lead orientation tool of FIG. 8 from a different angle; and

FIG. 10 shows just the second part of the locking mechanism.

In the following description like reference numerals will be used to indicate the same components over all the Figures.

FIG. 1 shows a perspective view of a flying lead orientation tool 1 and a mating tool 2 in accordance with the present invention. The flying lead orientation tool 1 has a first end comprising a first part 3 of a locking mechanism. The opposite end of the flying lead orientation tool 1 is attached to a schematically shown ROV.

The mating tool 2 has a first end comprising a second part 4 of a locking mechanism. The opposite end of the mating tool 2 comprises mating means, such as an extendible and retractable tri-probe for the mating and de-mating of stabplates on an underwater structure.

As can be seen in FIG. 2, the first part 3 of the locking mechanism comprises a substantially rectangular planar plate. The centre of the plate is hollow, and a pair of reinforcing struts join the opposite corners along the diagonals of the rectangle.

As can be best seen in FIGS. 3 and 4, the second part 4 of the locking mechanism comprises a slot which is substantially complementary in shape to the first part 3.

In FIG. 4, it can be seen that when the first part 3 is engaged with the second part 4, the second part 4 contacts the first part 3 at two separate points, i.e. the top surface of the plate and the bottom surface of the plate. This allows rotational forces to be transmitted from the flying lead orientation tool 1 to the mating tool 2. This is useful, as there is often a requirement to manoeuvre the mating tool 2 so that its mating means align with a stabplate which needs to be mated or de-mated.

Once the first part 3 is engaged with the second part 4, a retaining means (not shown) may be moved into a position in which it prevents the disengagement of the first part 3 from the second part 4. The retaining means comprises a latch which is moved by an actuator powered by the ROV.

The latch is initially in a first position in which it does not prevent the disengagement of the first part 3 from the second part 4, and the latch is biased towards this position by a biasing means (e.g. coil spring, leaf spring, elastomeric element, etc.). In order to move the latch into a second position in which it prevents the disengagement of the first part 3 from the second part 4, the actuator must overcome the force provided by the biasing means.

As the biasing means exerts a constant force urging the latch into the first position, the actuator must also provide a constant, greater force in order to maintain the latch in the second position. It is this mechanism that ensures that the locking mechanism is ‘fail free’: if the ROV loses power during the mating or de-mating of a stabplate, the actuator will also lose power. In the absence of the force provided by the actuator, the biasing means will move the latch to the first position, which will then permit the disengagement of the first part 3 from the second part 4, which in turn will allow the ROV to be separated from the stabplate and the underwater structure to which it is attached.

FIG. 10 shows a second part 4 suitable for use in the present invention. The second part 4 comprises a guide 5 for the first part 3. The guide comprises a slot that progressively narrows. This allows the first part 3 to fully engage with the second part 4, even if there is a slight misalignment between the two.

Although not shown in any of the Figures, it is possible to provide an urging means on the second part 4. This could take the form of a spring ejector located at the point where the front of the rectangular plate meets the rear of the slot. The spring ejector would provide a force to push the first part 3 away from the second part 4 when the latch moves back to the first position. The spring ejector could separate an ROV from an underwater structure if the ROV loses power, which in turn could aid retrieval from the surface.

The invention is not limited to the specific embodiments disclosed above, and other possibilities will be apparent to those skilled in the art. For example, an alternative mechanism could be selected to disengage the flying lead orientation tool from the ROV using for example a second ROV or hydraulic power source to initiate the disconnect, or even a fully automated system. 

1. A remotely operated vehicle comprising a flying lead orientation tool and a mating tool, wherein the mating tool is connected to the remotely operated vehicle via the flying lead orientation tool, wherein said flying lead orientation tool comprises a first part of a locking mechanism, said mating tool comprises a second part of the locking mechanism, said first part engaging with the second part to secure the mating tool to the flying lead orientation tool in use, and wherein the locking mechanism comprises a retaining means, said retaining means permitting the disengagement of the first and second parts when the retaining means is in a first position, said retaining means preventing the disengagement of the first and second parts when the retaining means is in a second position, wherein the retaining means is biased into the first position by a biasing means.
 2. A remotely operated vehicle according to claim 1, further comprising an actuator operable to move the retaining means from the first position to the second position, wherein the actuator requires a constant energy input to maintain the retaining means in the second position.
 3. A remotely operated vehicle according to 2, wherein the energy input is provided by electrical means.
 4. A remotely operated vehicle according to 2, wherein the energy input is provided by hydraulic means.
 5. A remotely operated vehicle according to claim 1, wherein the retaining means comprises a latch.
 6. A remotely operated vehicle according to claim 1, wherein the first part contacts the second part at two separate points when they are engaged with one another.
 7. A remotely operated vehicle according to claim 1, wherein the second part comprises a guide for the first part.
 8. A remotely operated vehicle according to claim 7, wherein the guide comprises a slot that progressively narrows.
 9. A remotely operated vehicle according to claim 1, wherein the second part comprises an urging means configured to urge the first part away from the second part.
 10. A remotely operated vehicle according to claim 9, wherein the urging means comprises a spring ejector.
 11. A method of connecting a flying lead orientation tool of a remotely operated vehicle to a mating tool comprising: providing said flying lead orientation tool with a first part of a locking mechanism; providing said mating tool with a second part of the locking mechanism; engaging the first part with the second part to secure the mating tool to the flying lead orientation tool; providing the locking mechanism with a retaining means, said retaining means permitting the disengagement of the first and second parts when the retaining means is in a first position and preventing the disengagement of the first and second parts when the retaining means is in a second position; and biasing the retaining means into the first position with a biasing means.
 12. A method according to claim 11, further comprising the step of: providing the remotely operated vehicle with an actuator operable to move the retaining means from the first position to the second position, wherein the actuator requires a constant energy input to maintain the retaining means in the second position.
 13. A method according to 12, wherein the energy input is provided by electrical means.
 14. A method according to 12, wherein the energy input is provided by hydraulic means.
 15. A method according to claim 11, wherein the retaining means comprises a latch.
 16. A method according to claim 11, wherein the first part contacts the second part at two separate points when they are engaged with one another.
 17. A method according to claim 11, wherein the second part comprises a guide for the first part.
 18. A method according to claim 17, wherein the guide comprises a slot that progressively narrows.
 19. A method according to claim 11, wherein the second part comprises an urging means configured to urge the first part away from the second part.
 20. A method according to claim 19, wherein the urging means comprises a spring ejector. 